TWI382688B - Power control method - Google Patents

Description

Power control method

The present invention relates to wireless communication systems, such as power control operations for downlink communication in various wideband code division multiple access (WCDMA) systems.

The primary resource for performing downlink communication operations in any WCDMA communication system is the carrier power of the base station. The maximum carrier power value has a certain restrictive relationship with the number of users that the base station can serve, as well as the service quality of the base station and the range of its service area. Each communication channel requires the base station to provide sufficient dedicated channel power to meet the quality requirements of the channel in relation to the block error rate during operation, and to provide end users with acceptable quality and acceptable quality. Communication service. However, another important factor that base stations must consider is the need to effectively use existing power resources to avoid using excess power resources beyond the required amount; therefore, base stations must constantly change (or adjust) the allocation of transmit power.

In the WCDMA system, both the uplink communication operation and the downlink communication operation (refer to the reference [1] described later) have standard functions for providing fast power control. The operation mode is a command by the user equipment (UE) to transmit a transmitter power control (TPC) to the communication network (ie, "power increase" or "power reduction"). The base station can use these commands to adjust the dedicated power for that particular User Equipment (UE). The base station uses its default calculation method and the received TPC command to adjust its power allocation in a stepwise manner to determine whether the user equipment should be previously allocated. A new power value adjustment operation that increases or decreases the power value. Any power control command made in the absence of power distribution saturation will be accepted by the base station. There are two alternative response measures related to the aforementioned preset power control algorithm, one of which is to reduce the risk of misinterpretation of the TPC command, and the other is to limit the setting of a sliding window size and a threshold. Power control power rise range.

The various standard power control algorithms used in 3GPP systems are primarily designed for the various situations in which the system can fulfill all service requirements and the preconditions under which mutual interference can be compensated. However, since the wireless communication environment varies from time to time, it may happen at any time that the base station does not have sufficient carrier power to satisfy the service requirements of all users, and may cause unstable operation of the system, and refer to the reference [2] described later. Various wireless communication systems usually provide license control devices and stop service devices, but these devices operate slowly and are not designed to handle system instability. Therefore, it is necessary to design a method that can handle the above situation in a short time within a short time range.

So far, several power control algorithms have been published in the industry. For example, in the reference [3] described later, it has been explained that when the power of the dedicated communication channel is increased, the original communication quality target is gradually lowered. In essence, this means that when the user asks the base station to increase the transmission power, it must accept the deterioration of the communication quality.

In the international patent application file of reference [4], the method for solving the above problem is to make more than two base stations in diversified communication. The transmitter output power of signals transmitted by a particular mobile station is decentralized. The transmitter output power used by each of the base stations to transmit information to the specific mobile stations is based on the power control commands transmitted by the mobile station and the time when the base station transmits the message to the specific mobile station. The transmitter output power and other parameters are adjusted. These adjustments can be performed using fixed or continuous stepping.

Refer to the descriptions in references [5], [6], and [7] for the adjustment operations performed by various parameters such as TPC history, action speed, and bit error probability.

Although the above various problem solving methods can achieve better downlink communication power control effects, there are still several related problems in these methods. A disadvantage of the power control method employed in the prior art is that there is no such thing as an over-allocation of the transmitter output power, or a temporary shortage of available transmitter power. Insufficient power resources will also cause all communication channels to be "victimized" together, thus making individual mobile stations face a more unpredictable dilemma.

Therefore, it is indeed necessary to develop a method for improving the power control of the downlink communication.

One of the general objectives of the present invention is to provide a link communication power control method that can improve the operational stability of a wireless communication system. One of the specific objectives of the present invention is to achieve efficient use of power data in a communication system that shares resources. Another goal is to eliminate the risk of temporary use of transmitter power. Another goal is to provide a power control mechanism that can be used by various WCDMA systems.

The above objectives can be in accordance with the annex to this specification, the scope of patent applications The design content is achieved.

In short, the present invention provides a complete power control method for downlink communication operations. After receiving the transmitter power change request from any mobile terminal, the base station shall immediately determine a power control parameter based on its available total transmitter power, for example: a maximum specific link transmitter power value, one Stepped power change range, or a power increase probability. Thereafter, the base station can utilize the power control parameter to assign an appropriate transmitter power to the communication channel. When a base station allocates transmitter power to an individual communication channel, the power requirements of all communication channels served by the base station should be considered in a comprehensive manner (rather than just considering the communication channel controlled by it at the time). More efficient power control methods and the goal of eliminating the risk of over-allocating power.

In various embodiments of the invention that may be employed, the total amount of transmitter power available at the time is utilized, and other factors related to a particular link code power and/or priority of the communication channel demand are considered. Perform power control operations after entering parameters.

In accordance with other aspects of the present invention, a transceiver node is also provided, as well as a communication system.

1 is a schematic diagram showing the architecture of a WCDMA communication system which can be designed by the present invention. The system 100 in the figure includes a "Radio Access Network" (RAN), such as a Universal Regional Radio Access Network (UTRAN), and a core network 130. The RAN is used to perform functions related to radio communication and is responsible for the user equipment 110 (eg, mobile phones and laptops) The computer establishes a communication channel with the rest of the network. The RAN typically includes a number of base transceiver stations (BTS) 122, also referred to as "Node Bs" and a number of "Radio Network Controllers" (RNCs) 124. Each BTS provides services to a number of mobile terminals within its communications coverage area and is controlled by an RNC. RNC's standard features include: allocation frequency, code extension or encryption processing, and channel power level control.

The RNC 124 can provide access operations to the core network 130. For example, it includes various switching centers, support nodes, and databases that operate in conjunction with any Global System of Mobile Communications/General Packetized Radio Service (GSM/GPRS) core network, and typically also includes multimedia processing equipment. The core network described above communicates with various external networks 140, such as the Internet, the Public Switched Telephone Network (PSTN), the Integrated Services Digital Network (ISDN), and other "common terrestrial mobile networks." Road" (PLNN).

In practice, most WCDMA networks contain more complex network elements and nodes than the one shown in Figure 1.

The method provided by the present invention is particularly applicable to WCDMA communication operating systems, such as various "High Speed Downlink Shared Channels" (HS-DSCH) systems. However, the reader should be aware that all other communication systems that are available to most users simultaneously sharing the same power resources are within the scope of the method of the present invention. If the strong interference caused by the use of power by a node in the system is sufficient to affect the operators of the neighboring nodes, such systems are also within the scope of the method of the present invention. Such systems include, for example, time multiplexing or code multiplexing orthogonal frequency division multiplexing processing systems (OFDM) and time division multiple access (TDMA) systems, And systems that use Multi-Carrier Power Amplifiers (MCPA).

In order to expand the operating energy of a wireless communication system (for example, a "CDMA" system), it is necessary to have a mechanism for effectively controlling the uplink and downlink transmission power. Power control is performed on the downlink (forward) communication channel, in particular to enable the base station to provide a signal strength that satisfies the user for each mobile station. Typically, in operation, the mobile station meters the strength of the received signal transmitted via the downlink communication channel, and then, based on the measured values, the base station is required to adjust its signal transmission power.

As described in the "Technical Background Notes" section above, standard fast power control (1500 Hz) is provided for the transmit signals of both the uplink and downlink communication channels in any WCDMA system. The user equipment (UE) can transmit the power control command signal TPC(t) to the communication network at a fast operational performance of 1500 times per second, and each command will indicate a "power boost" or "power reduction" message. Based on such an instruction, the base station can change the dedicated power level used for transmitting signals to the mobile station, that is, UE p(t). The aforementioned 3GPP standard downlink power control algorithm includes a preset calculation value and two alternative values (refer to the description of reference [1]). The preset calculation method uses the received transmitter power control command TPC(t) to update the logarithmic adjustment ratio (in dB (decibel) value) in a step adjustment manner in each time slot t, and Calculate the magnitude of the power adjustment according to the following formula (the magnitude is in +1 or -1): p(t + 1) = p(t) + Δ TPC(t) [dB] The Δ in equation (1) is the step adjustment amplitude expressed in dB. The step adjustment can be set to four digital values: 0.5, 1, 1.5 or 2 dB. The UTRAN network must be able to support the 1 dB step adjustment range. For other step adjustments, you can choose it yourself. The only reason for not accepting the "Power Control Directive" is that the power distribution has reached saturation, that is, the transmit power has reached the upper and lower power limits set by the operator (represented by p_upper and p_lower respectively). This means: p( t + 1) =max( p _ lower, min( p _ upper, p(t) + Δ TPC(t))) [dB] (2)

The first option is to limit the phenomenon in which the TPC instruction is interpreted incorrectly. Each TPC command repeats in three consecutive time slots, so the actual update (adjustment) rate drops to 500 Hz. The second option is to permit the change of the transmit signal power requirement by setting a sliding window range Swin to correct the sum below the threshold th: The TPC _sum in the formula represents the _sum of the past Swin corrections, namely: .

The basic knowledge of the present invention is that, according to the distribution status of the total power of the system signal transmission, the dedicated power value of the signal transmitted by any relevant communication channel is changed, and the most effective downlink communication power control effect can be obtained. Since the total power transmitted by each base station signal is a limited resource, the optimal operating conditions of the system should be controlled based on this parameter. Measuring the total value of the signal transmission power of the base station and using the method designed by the present invention to control the system In operation, a power control mechanism that directly responds to changes in the current critical power parameters is obtained.

In order to improve the stability of the system operation, the present invention provides a system operation overall control method by performing downlink communication power control according to the change of the total power of the base station transmitter. A detailed description will be provided below with reference to FIG. 2, which has a transceiver node 122 and two mobile communication terminal stations 110. The transceiver node 122 can communicate with the mobile communication terminal stations via associated wireless communication channels.

The transceiver node 122 is typically located on one side of the network, such as a radio access network of the UTRAN type, which enables various wireless communication units to operate in conjunction with the rest of the network. The transceiver node may include or cooperate with a (wireless communication) base station, such as a "Node B" or a BTS and/or a device having radio control functions, such as an RNC or a Base Station Controller (BSC) Operation. In the following description, the transceiver node generally refers to a base station.

The wireless communication units 110 (also referred to as user equipment, mobile nodes, mobile stations, etc.) in the figure are cellular telephones. However, the present invention is also applicable to communication operations with other types of wireless communication units, including personal digital assistants and laptops.

As shown in Figure 2, the total transmitter power (or "downlink communication carrier power") of the base station is P _DL . The total power of the transmitter contains the shared power (for example, to transmit the pilot signal to the end users via the shared channel) and the dedicated transmit power when transmitting signals to certain mobile terminals. The existing transmitter total power P _DL (t) shown in the figure represents all downlink communication power resources (including shared power and specific link power) used by the transceiver node at a specific time point (t). In other words, the total power of the transmitter is the sum of all the transmit powers allocated by the transceiver node at the time of operation. The existing available downlink communication power resources represent the maximum transmitter (downlink communication) power P _{DL, max} at the particular transceiver node.

The figure also shows the dedicated transmitter (downlink communication) power p _{i of} each communication channel (i), also known as the individual communication channel downlink communication code power. The current (current) specific link transmitter power p _i (t) in the figure represents the downlink communication power allocated by the base station to the communication channel i at a certain time point t. The prior art presets the code power allocation amount according to the value obtained in the previous equation (1), but in accordance with the design of the present invention, the power distribution operation is processed in the modified manner described below.

Each wireless communication unit 110 transmits a power change request (eg, a power boost command) to the base station 122. The difference from the above-mentioned preset power control method is that not all of these requirements are accepted. The base station determines whether such requirements should be accepted based on the total power of the transmitters available at the time, or whether all or part of the request should be rejected. The determination value of the dedicated power of each communication channel is expressed by one or several power control parameters, and these parameters are preferably directly or indirectly related to a maximum value or a power change limit of the specific link transmitter power associated with the item. . The power control parameter is determined by the base station based on the total power of the transmitter that it can utilize at the time, and is used to assign a power value to the signal transmitted by the transmitter to an individual communication channel. Therefore, the assigned transmitter power value P _{DL of the} communication channel i depends on the total available downlink communication power p _i .

Figure 3 is a flow chart showing the operation of a downlink communication power control method summarized in accordance with the main principles of a preferred embodiment of the present invention. In step S1, the base station receives a transmitter power change request sent by a mobile terminal via a wireless communication channel. This requirement may, for example, include a standard WCDMA TPC command that can be processed by the method of the present invention. This method is particularly useful for dealing with repeated requests for increased power.

After receiving the above transmitter power change request, the base station can determine at least one power control parameter based on the total transmitter power value available at that time in step S3. In this step, it is preferable to perform a determination of the power control parameter by using a predetermined power distribution function that can cause a smooth transfer operation when the total available power of the available transmitter approaches the maximum limit at that time, or according to a preset The total power threshold of the transmitter determines the power control parameter. Preferably, the power control parameter is related to a specific link transmitter power ceiling and/or the specific link transmitter power rate of change. Preferably, the total power of the base station's transmitter can be continuously measured by the base station itself (step S2). However, in some embodiments of the invention, it can be determined at any location and sent to the transceiver node for use. It can be seen from the following description that the total available power value of the existing transmitter is not necessarily the only input parameter that affects the aforementioned power control parameters (except the TPC value). The power control parameter may also be a total value of power control parameters obtained by combining several individual power control parameters calculated using different input parameters.

Finally, in step 4, the base station assigns transmitter power to the associated communication channel in accordance with its determined power control parameters. Power control The number can affect the actual amount of power allocation either directly or indirectly. An example of indirect impact is to indirectly affect the power value (p(t)) in equation (1) above using a power control parameter related to the bit rate that can be tolerated by the communication channel. The operation program shown in Figure 3 is usually repeated in any communication channel in operation, because the mobile terminal operating with this communication channel will repeatedly propose to increase power or reduce power as the communication situation changes. Requirements.

With the method of the present invention, the operational behavior of each communication channel can be adjusted according to changes in all shared power resources. The traditional downlink communication power control system is completely implemented with individual communication channels. Because each mobile terminal user in the same system does not know the current status of the allocated power of other links, there is a serious occurrence of a situation in which the transmitter power is over-allocated or temporarily used. However, if the power used in conjunction with the allocation of the transmitter power of all other communication channels served by the same base station (including all links or any of its packet links) is considered in the overall design, a provision can be provided. More efficient power control mechanism. One of the biggest advantages is that it is not possible to attempt to over-allocate existing available power resources in the network portion. Thus, the risk of temporary use of the transmitter power can be eliminated and the stability of the system operation can be ensured.

Another advantage of the present invention is that the base station can smoothly respond to the power increase request from the user equipment. The allocated power can be increased in a smooth manner as the transmitter power ceiling is approached. Power control is preferably performed over a relatively short period of time, and can be quickly completed with all power distribution conditions changing. Into the adjustment operation.

The present invention can improve the operational stability of the system by utilizing a method of performing power control within the network and taking into account the current power usage of the base station. Due to the improved system operation stability, all users in the system can enjoy the benefits of the base station service energy and quality improvement. In general, all kinds of wireless communication systems will face the problem of how to balance the imbalance between system coverage, service quality and system load. In this regard, the most important issue is to strike a balance between the coverage of the service and the stability of the system operation, that is, the existing resources should be fully utilized (referring to the base station downlink communication power). The system has good service coverage under low load conditions and good system operation stability under high system load. The method provided by the invention can achieve the effect of properly balancing the above factors, for example, when the system load increases, the system service coverage is reduced, or the effect of weak degradation of quality is provided.

The design according to a preferred embodiment of the present invention is based on the total transmitter power of the base station (ie, the downlink communication carrier power) and the dedicated transmitter power allocated to the individual communication channel (ie, the downlink communication code power). The combined value of the two parameters determines the above power control parameters. Thus, power control operations are related to the use of individual specific connected resources and the overall resource utilization of all links. Therefore, the phenomenon of saturation of power distribution can be avoided, and the smooth transition operation between different communication channels when the total power of the transmitter is high (ie, close to P _{DL, max} ) can be distinguished. For each communication channel that uses a lot of coded power, it can be handled by setting some strong restrictions. Moreover, this solution is usually easy to implement and can be performed without sending any additional signals (for example, between the RNC and the Node B in the WCDMA system described above) because the present value of the carrier power and the encoding power are present. The value can be measured in the base station.

Preferably, the method for setting the power (use) limit according to the method of the present invention preferably utilizes an adapted dedicated coding power maximum value P _i,max ; a possible factor π _{i for} accepting any power change request; and/or an adapted power step The way to adjust the range Δ _i is. The following text provides detailed descriptions of the transmitter power control method performed by these related power control parameters in accordance with the specific example principles of the design of the present invention. These power control calculation methods are intended to obtain the value [W] of the linearly varying data and the numerical range [dBW or dBm] expressed in logarithm. However, if no other instructions are provided, the scope indicated by the straight line should be used as the basis for setting.

Dedicated coding power maximum

A preferred method for reducing the probability of any communication channel causing the downlink communication power is to reduce the maximum value of the dedicated coding power P _i,max that can be assigned to any individual dedicated communication channel, that is, the dedicated communication channel can be The upper limit of the allocated power. The calculated maximum coded power maximum can be considered as a function of the transmitter's downlink communication total power P _DL : P _i,max =f(P _DL ). When most of the downlink communication power has been allocated to the relevant communication channel, each communication channel is usually limited by a lower-chain communication-specific coding power maximum. The higher the downlink carrier carrier power, the lower the encoding power.

In the first example represented by the following formula (4), the above-mentioned dedicated coding power maximum value, when the downlink communication carrier power value is greater than P _{DL, low} value but lower than P _{DL, high} value, will be at P _{max , lower} and P _max, the range of _upper changes. Otherwise, P _{i, max} = P _{max, upper} ; as shown in the following formula: p _i,max = p _max , _upper - (p _{max, upper} -p _{max, lower} ) (P _DL - P _DL,low )/ (P _DL,max - P _DL,low ) (4)

According to the second example represented by the following formula (5), it is a relatively simple method, wherein the maximum value of the dedicated coding power can be regarded as whether the carrier power value is lower than a threshold value P _{DL, low} . There are two different values, as shown in the following formula:

The reader should be aware that this P _DL value can also be used in conjunction with one or more other input parameters when determining the maximum value of the downlink communication code power. When one or more input parameters are used, each input parameter can be used alone to calculate the maximum power value, and the total value of these calculation results is used as the maximum value of the dedicated coding power. In a specific example using two different input parameters, the total power value is calculated according to the following formula (6): p _{i,max,aggregate} =min (p _{i,max,input 1} , p _{i,max,input 2} ) (6)

Power increase probability

In a WCDMA system using a preset power control algorithm, after receiving a transmitter power increase command sent by a wireless communication unit, the base station gradually increases the rate according to a step-up rate Δ. Item-specific channel power value. Only when the preset dedicated coded power maximum value is reached, the power up operation of the accepted case will stop. A specific example can be employed in the present invention. It uses a programmed probability π _inc,i (possibly zero) as a power-up probability to determine whether to accept any of the received power boost requirements.

When most of the power of the available downlink communication carrier power has been allocated, (base station) has a good reason to be cautious to avoid performing the power up operation based only on the power boosting requirements proposed by the wireless communication unit. Therefore, it is often necessary to set a higher downlink communication carrier power to a lower power up probability value. The base station may make a decision not to accept a certain power increase request based on one of two consideration criteria. The first is that the specific link transmitter power value p _i (t) originally allocated remains at the same level; the second is that the value is decreasing in the speed of the step rate Δ. The latter criterion is a more effective criterion for suppressing the excessive use of transmitter power in a communication channel.

In the following example expressed by the formula (7), when the power reduction value in the latter criterion is greater than P _{DL, low} and lower than P _{DL, max} , the line rate is changed in accordance with the downlink carrier carrier power change rate. The way of the relationship performs the power up operation. Otherwise, π _inc,i =1, (n is a parameter).

π _{inc, i} = 1 - ((P _DL - P _DL,low )/ (P _DL,max - P _DL,low )) ⁿ (7)

FIG. 4 and FIG. 5 are diagrams showing the operation performance of the power consumption control function as the power control parameter according to the method of the present invention and performing the downlink communication power control according to the current load condition, according to the method and the conventional preset power control. The method is different. The two figures in Figures 4A-B are based on prior art for a certain continuous Find the operating performance graph of the coding power provided by the communication channel used by a certain wireless communication unit that allocates more power. In this case, the base station distributes the transmitter power to the particular communication channel in accordance with the standard control algorithm represented by equations (1) and (2) above. The normal coded power value assigned in each of the associated time slots is included in FIG. 4A, and the power change occurring after the last time slot is shown in FIG. 4B. The two figures clearly show the linear power adjustment effect of the logarithmic power control operation. The figure shows that when the communication channel is matched by the coded power (before the saturation condition at time slot 30), the power-up value in watts is gradually increased by the exponential ratio. This phenomenon constitutes the unstable nature of this traditional power control algorithm.

However, if the load-based power control method provided by the present invention is employed, a more excellent dramatic power boosting effect can be obtained. Figure 5A shows the power increase probability calculated by the parameter of n = 2 in the manner indicated by equation (7). Figures 5B-C correspond to the situation of Figures 4A-B. However, this time, the power control operation is performed based on the P _DL and the encoded power value and using the power control probability value shown in FIG. 5A. When the coded power value and the carrier power value are increased, the power increase probability is lowered, and the power value and the carrier power value are increased to near the coded power and the carrier power maximum value, thereby obtaining superior power. Control efficiency.

The second example, expressed by the following equation (8), is a relatively simple method in which the power improvement probability is based on whether the carrier power is lower than the P _DL, the change of the _low value is at the value 1 and another fixed value π _inc Relative change between _{lower and lower} .

When most of the downlink communication code power has been allocated, there should be sufficient reasons to deal with the power increase requirements with a more cautious approach. As explained above, one particular example of a method design in accordance with the present invention performs power control operations in accordance with the total transmit power values available to the base station and the dedicated power values that can be assigned to each communication channel. Applicable to this case, the power increase probability value is taken as its power control parameter, that is, the power increase probability value is used as a function of the downlink communication power and the downlink communication coding power: π _{inc, i} = f(P _DL , p _i ). In this case, when the downlink communication code power value is high, it usually means that the power increase probability is low. In a specific example represented by equation (9), the total power increase probability is the product of the power increase probability value calculated using the downlink communication carrier power value and the downlink communication code power.

π _{inc, i, aggregate} =π _{inc, i,} P _DL π _{inc, i, pi} (9)

The factor π _inc,i,pi in the above formula can be calculated in the following manner (10) or (11). When calculating by formula (10), if the dedicated coding power p _{i is} greater than p _low but less than p _{max, i} , the power increase value will change in a straight line relationship with the dedicated coded power value. Otherwise, π _inc,i =1, (where n is a parameter)

π _{inc, i} = 1 - ((p _i - p _low )/ (p _max,i - p _low )) ⁿ (10)

The second case, represented by equation (11), adopts a simpler method, and its power-increasing probability value is based on whether the carrier power is lower than the p _low value at the value 1 and another fixed value π _{inc, lower} Relative change.

Any other power control algorithm that uses the total transmitter power value and one or more other input parameters as the total value of the input parameters as the total number of transmitters can be used. When using one or several other input parameters, each individual input parameter can be used to calculate the power increase probability, and the total value of the power increase probability values calculated by each single input parameter is taken as the power increase probability determined in this case. value. Input 2 and input 3 therein may (but are not required to) include the specific link transmitter power described above.

π _{inc, i, aggregate} =π _{inc, i,} P _DL π _inc , _{i, input 2} π _{inc, i, in} p _{ut 3} (12)

Power control step adjustment unit (range)

In the preset power control algorithm used in the WCDMA system, after receiving the power increase TPC command from a certain mobile terminal station, the base station adjusts the unit Δ (in dB) according to a fixed step. The dedicated power value of the communication channel. The power up operation stops when the boosted power value reaches the original dedicated coded power maximum.

In the algorithm provided by the present invention, it is suggested that the power control step adjustment unit (range) Δ: Δ _i = f (P _DL ) should be adapted according to the condition of the total available downlink communication of the base station. The unit of power up and down (range) can be used for up or down operation. The power increase request sent by the mobile terminal station may be zero or a negative value Δ after acceptance. Therefore, it should be a power increase request that is not accepted (or rejected). Because only the step up adjustment unit (range) is the important factor affecting the stability of the downlink communication. Therefore, the step adjustment unit (range) can sometimes be limited to the function of only allowing the upward adjustment. And at the same time keep the downward adjustment units (ranges) at a constant level.

Sometimes, (for example, when the step adjustment unit (range) cannot be directly adjusted), the power adjustment operation can be performed after each interval (N) time slots. The value of the (N) parameter should be N= the lowest value _{X (Δ norm / Δ desired)} , the Δ _norm is the adjustment unit of the system may be employed (e.g.: 1 dB).

If most of the power of all downlink communication carrier power has been allocated, the processor should be particularly cautious when preparing to increase power in full compliance with the requirements of the power-up instructions. When the power control operation is performed using the method of the present invention, any higher downlink communication carrier power typically results in a decrease in the upward step-up unit (range), in a particular embodiment of the invention. The change of the unit range of the upward stepping high power has a linear relationship with the current variation of the downlink carrier carrier power value, and is reduced to zero when the adjusted carrier power value approaches its highest level. . This characteristic can be expressed by the following equation (13), where Δ _param represents a certain parameter value, and Δ _norm represents the maximum value of the power step adjustment unit (range).

Δ _i =min( Δ _norm , Δ _param (P _DL,max - P _DL )/ P _DL,max ) (13)

Furthermore, in some cases, different step-adjustment units (ranges) for up-swing up and down-down may be considered. For example, when the communication system load is low, a longer upward step-up step unit is used. And performing the power control operation down the step unit, or vice versa. In a specific example, depending on the current variation of the downlink carrier power, the upward and downward stepwise adjustment units (ranges) are respectively adjusted in a linear response manner. When the carrier power value is close to its maximum value, the adjustment unit of the upward step-up is reduced to zero, and when the carrier power becomes lower, the adjustment unit of the downward step adjustment is reduced to zero. This relationship is expressed by the following equation (14), where Δ _param is a parameter, Δ _{norm is} the maximum value of the power adjustment unit (range), and P _{DL, lower} is a lower carrier power criterion. Bit.

Δ _{i, upward} =min( Δ _norm , Δ _param (P _DL,max - P _DL )/ P _DL,max ) (14)

Δ _{i, downward} =min( Δ _norm , Δ _param (P _DL - P _{DL, lower} ) / (P _{DL, max} - P _{DL, lower} ))

As for the aforementioned control parameters, more than one input parameter can be used when determining the step adjustment unit (range). And calculate each individual step adjustment unit (range) for each input parameter, and use the total value of the individual adjustment unit (range) values calculated as the step for actually performing the power control operation. Adjustment unit (range). In a specific example using two different input parameters, the total value of the individual adjustment units (ranges) is calculated by the following equation (15): Δ _{i, aggregate} =min( Δ _{i, input 1} , Δ _{i, input 2} ) (15)

In another specific example that may be employed, a combined value of the transmitted downlink communication coded power and the transmitted downlink communication carrier power is used: Δ _i =f(P _DL, p _{i, code} ). The stepwise adjustment unit (range) value can be calculated in a linear relationship with the downlink communication carrier power and the downlink communication coding power [watt value], and when the carrier power and/or coding power are close to the respective At the maximum level (as shown in equation (16) below), it is reduced to zero.

Δ _i =min( Δ _norm , Δ _param (P _DL,max - P _DL ) (( p _i,max - p _i ) (16)

The power control operation is performed by using the combined value of the chain communication carrier power and the downlink communication code power calculated according to equation (16), as shown in FIG. 6 "power step adjustment unit (range) and downlink communication carrier carrier The relationship between power and downlink communication coding power is shown in the graph. In this case, the maximum value of carrier power P _{DL, max} is 20 watts, the maximum value of coding power p _i,max is 1 watt, Δ _param =0.1 dB, and Δ _norm =1 dB. Obviously, the stepwise adjustment units (ranges) with extremely small values are applied at high carrier power and/or high coding power, and the system can effectively increase the respective power values in a dramatic manner at high loads. As shown in FIG. 6, the power increase probability value calculated by equation (16) can also be used as the coding parameter.

The above results can be directly applied to such situations, in which case the extremely small power increase probability values can be applied at high carrier power and/or high code power.

In some cases, the power step adjustment unit (range) and each of the maximum power values can be normalized. That is, the system is more cautious when it comes to raising the transmitter power for high data rate communication service operations. In addition, when using this method, various calculation operations can be performed without being affected by the maximum transmitter power value of the base station and the type of signal-carrying media. There are three examples of these calculation methods: Δ _i =min( Δ _norm , Δ _param (P _DL,max - P _DL ) ( p _i,max - p _i )/ p _i,max ) (17)

Δ _i =min( Δ _norm , Δ _param (P _DL,max - P _DL ) ( p _i,max - p _i )/ P _{DL,ma x} ) (18)

Δ _i =min( Δ _norm , Δ _param (P _DL,max - P _DL ) ( p _i,max - p _i )/( p _i,max P _DL,max )) (19)

A numerical case is used to illustrate the above situation, assuming that the voice communication service has a p _i,max value of 1 watt, and the video telephony service (data transmission rate is 64 kbps) has a p _i,max of 4 watts. When the normalization processing is not performed on the maximum encoding power, the step power adjustment unit (range) is 0.5 watts for the voice communication service power, and the video telephone service power is 3.5 watts, which are the same. This means that the system performs the adjustment process more carefully when performing the adjustment processing on the signal power required by the high data rate user.

Although the various power control algorithms described above use power boosting probabilities and stepped power adjustment units (ranges) to perform power control operations on parameters, the method employed by any of these control parameters is generally applicable to other controls. parameter. Therefore, the formulas used in performing the power step adjustment unit (range) can also be applied to the case where the power adjustment is performed using the power up-regulation rate, and vice versa.

In each of the above examples, various actual (rather than standardized) power parameters are used. However, sometimes (for example, when the base station uses different downlink communication carrier power maxima, it is also considered to use the chain communication carrier power as the input parameter in relation to the carrier power maximum. Similarly, in other cases For example, when different communication channels have different downlink communication coding power values, the chain communication coding power related to the maximum value of the coding power may also be considered as the input when performing the power control algorithm with the coding power. Parameter if its carrier power parameter consists of a downlink communication carrier The above methods can still provide the same effect when the power is replaced by the same parameter and the coding power parameter is replaced by a parameter different from the maximum value of the downlink communication coding power.

In addition, since various input power data usually have rapid and significant changes, in many cases, a plurality of filters are added to the relevant portions of the aforementioned downlink communication control function. With regard to the current and previous values of various input parameters (eg, P _DL and p _i ), these fast and significant changes can be reduced after filtering, so that the power control parameters are only slow. Input data for changes.

According to another aspect of the present invention, the design of the downlink communication power control operation is performed based on the combined parameters of the total power of the transmitter and the individual communication service priorities of each communication channel in the system. The main idea of this method is to adopt a proactive steategy strategy as a measure to avoid the power increase requirements of certain communication channels and to prioritize the maintenance of normal communication services of other communication channels. All communication channels are subject to poor service quality. When the above measures are taken, the power control parameters used to allocate the transmitter power to a specific communication channel are based on the total available power of the available transmitter, and the communication channel provides the communication operation. Parameters such as priority data are used to determine the power control. Preferably, the aforementioned communication channel specific data includes one or several so-called priority level indicators DPI. Therefore, the amount of power p _i that should be allocated to the communication channel i depends on the P _DL and DPI parameters of the particular communication channel DPI _i .

The above DPI parameters represent a particular communication channel in a predetermined manner. The importance/relevance/priority of providing communication services at a particular point in time. This parameter is usually used to describe the current or future operation of any end user and terminal station, and may contain descriptive information about the user, device and/or communication channel. The parameter indicating the priority level is obtained by collecting it by means of a measurement method or a data holding unit (for example, a network control unit) or a database of the network itself. These priority metrics include the following:

Category and level of mobile communications

When some mobile communication terminals provide the same service (in the same wireless communication environment), the power obtained from the base station is greater than that obtained by other terminals. Therefore, the category of mobile terminals can be used as an indicator of priority. It can be expressed by the type of the mobile terminal. However, in a design that may be used in a specific example, it is recommended that the level of the mobile terminal be automatically provided. The actual performance or input signal power requirement of any mobile terminal can be determined by the network part and the level of the terminal can be defined accordingly. For example, when connecting to a specific reference communication partition, use the required lower chain. The data of the communication coding power amount is determined by its level; the IMIE number; the data segment error rate (if the data transmission service is provided). Such automatic grading operations may be based on stored or measured data relating to a particular communication channel.

User line level

If it is intended to prioritize an individual or a batch of subscriber line levels in front of other subscriber line levels, the indicator s _i representing the subscriber line level is a useful input, for example, for the operator to pay Gaozhi customers provide gold subscriber lines with better service quality.

Connection time

The longer the mobile terminal is connected to the communication channel, the greater the chance that the communication channel will be restricted. Therefore, the continuous connection time t _c from the start of the connection time of a certain mobile terminal to a certain communication channel is a reference parameter with reference value.

Data service feature

In order to provide data services, current or expected user operational behaviors may be provided using the current values of certain data service features to determine the priority of communication operations between different communication channels. These parameters are usually measured on the network side (preferably at the RNC) and may include the amount of data transmitted, the amount of data scheduled, and/or the amount of data located in the buffer prior to transmitting the data. Therefore, a larger amount of data usually indicates that the communication channel has a higher priority for receiving data. Furthermore, the amount of power allocation can be determined based on one or more data related to the characteristics of the data packet. The relevant information includes: the length of the data packet (longer data packets are provided with prioritized information; data subcontracting categories; and/or elapsed time since the last data was transmitted; and error statistics with data segments) And/or data segment re-issue DPI data related to statistical data.

The method of performing downlink communication power control according to the combined data of the total transmitter power and the operation priority level related to each relevant communication channel can achieve the purpose of improving the stability of the system operation in a long-term or short-term manner. This specific example of the invention facilitates the design of more sophisticated power control functions (mechanisms) and more "fair" power distribution efficiencies.

Therefore, it is preferable to perform the power control method disclosed in the present invention by using the above various power control parameters p _i,max , π _inc,i and Δ _i . In accordance with the instructions provided in this document, a single control parameter may be utilized, or two or all of the control parameters may be used, depending on the circumstances of any particular power control request. Power control operations may also be performed in various embodiments of the present invention using various parameters related to power, including other various parameters directly or indirectly related to the power variation rate of a particular coupled transmitter power.

For systems that provide data transmission services, the target quality of a communication channel can be replaced or added to the various power control parameters listed above. This quality objective should set out the service objectives required for a communication channel. The data segment error rate (BLER) quality target of the WCDMA system is one of the examples; that is, the ratio between the number of erroneous data segments and the total number of transmitted data segments is an example.

The above description is provided with reference to the specific embodiments shown in the drawings, and it should be understood that those skilled in the art can also adopt the same methods as the published features, as well as various modifications and changes. Therefore, the scope of application of the method of the present invention should be limited only by what is stated in the scope of the patent application to which the specification is attached.

references

[1] 3GPP, Physical Layer Operating Procedure (FDD), Technical Specification TS 25.214.

[2] Gunnarsson, F. and Gustafsson, F. Power Control with Time Delay Compensation Technology, published in September 2000 at the Automotive Communication Technology Research Society in Boston, Massachusetts, USA Method Text.

[3] U.S. Patent No. 5,574,982 issued to M. Almgren et al.

[4] International Patent Application No. WO 02/35731 A1 by Telefonaktiebolaget LM Ericsson.

[5] International Patent Application No. WO 00/04649 filed by Nokia Networks OY Corporation.

[6] European Patent Application No. EPO 815 656 B1 by Nokia Corporation.

[7] US Patent No. 6,311,070 B1, filed and approved by Wen Tong, Rui and R. Wang.

100‧‧‧WCDMA communication system

110‧‧‧User equipment

122‧‧‧Base transceiver station

124‧‧‧ Radio Network Controller

130‧‧‧core network

140‧‧‧External network

ISDN‧‧‧Integrated Services Digital Network

PLMN‧‧‧Common Ground Mobile Network

PSTN‧‧‧Public switched telephone network

TPC‧‧‧Transmitter Power Controller

BSC‧‧‧Base Station Controller

P _DL ‧‧‧Transmitter (downlink communication) total power

p _i ‧‧‧ transmitter (downlink communication) power for each connection path

p _i (t)‧‧‧ (currently) specific link transmitter power

REQ‧‧‧Power change requirements

The reader should be able to understand the contents of the present invention, as well as its various objects and advantages, as shown in the following drawings: FIG. 1 is a schematic diagram showing the structure of an operating system of an exemplary WCDMA communication system using the method of the present invention. 2 is a schematic diagram showing the operation of transmitting a downlink communication power control message according to the method of the present invention; FIG. 3 is a flow chart showing the operation of the downlink communication power control method according to a specific example of the present invention; FIG. 4A-B The figure shows the coding power and the coding power improvement amount obtained by the conventional power control; FIG. 5A-C shows the curve of the power improvement probability, the code power and the code power improvement amount according to a specific example of the present invention. Figure; and Figure 6 is a graph showing the relationship between power control parameters, coding power, and carrier power in a specific embodiment of the present invention.

110-1, 110-2‧‧‧User equipment

122‧‧‧Base transceiver station

P _DL ‧‧‧Transmitter (downlink communication) total power

p _i ‧‧‧ transmitter (downlink communication) power for each connection path

REQ ₁ , REQ ₂ ‧‧‧Power change requirements

Claims (32)

A method for power control in a communication system (100), the communication system (100) comprising a transceiver node (122) communicable with a plurality of mobile terminals (110), the method comprising the following steps Receiving, at the transceiver node, receiving a transmitter power change request from one of the mobile terminal devices via a wireless connection; determining a step at the transceiver node, according to one of the transceiver nodes The existing total transmitter power determines at least one power control parameter for the connection; and an allocation step of assigning transmitter power to the link based on the determined power control parameter. The method of claim 1, wherein the existing total transmitter power substantially represents all downlink power resources, shares and specific links for the transceiver node (122) at a particular point in time. The method of claim 1, further comprising the step of measuring, by the transceiver node (122), the existing total transmitter power. The method of claim 1, wherein the determining step is further based on the transmitter power of the existing particular link of one of the links. The method of claim 4, wherein the total transmitter power is downlink carrier power, and the specific link transmitter power is downlink code power. The method of claim 1, wherein the determining step is further based on specific link information indicating a priority level associated with the link. The method of claim 6, wherein the specific link information comprises selected from the following Group information: action type, mobile class, subscription class, link time, amount of data transferred, amount of data in staging, packet length, packet type, time since the last packet, Block error statistics, as well as block retransmission statistics. The method of claim 1, wherein the power control parameter is related to a maximum of one of the specific link transmitter powers. The method of claim 1, wherein the power control parameter is directly or indirectly related to a power change rate of the specific link transmitter power. The method of claim 9, wherein the power control parameter is related to a probability of granting. The method of claim 9, wherein the power control parameter is related to a step size of a power change. The method of claim 1, comprising the steps of: combining, at the transceiver node (122), combining at least two power control parameters according to different input parameters into an aggregate power control parameter; and utilizing the aggregate power control parameter The specific link transmitter power is allocated in the allocation step. The method of claim 1, wherein the determining step comprises performing a predetermined power control function representative of a smooth transition behavior when the total total transmitter power of the transceiver node (122) is close to a maximum total transmitter power value. . The method of claim 1, wherein the determining step comprises determining the threshold value based on one of the total transmitter powers and determining the power control parameter. The method of claim 1, wherein the determining step is based on the total transmitter The current and previous values of power. A transceiver node (122) is operative to communicate with a plurality of mobile terminals (110) in a communication system (100) using a power control component, the transceiver node including: a receiving component received from the wireless link a transmitter power change request of one of the terminal devices; determining a component, determining at least one power control parameter of the connection according to an existing total transmitter power of the transceiver node; and assigning a component according to the determined power control parameter Assign transmitter power to the link. The transceiver node of claim 16, wherein the existing total transmitter power is actually represented at a particular point in time for all downlink power resources, shares, and specific links of the transceiver node (122). The transceiver node of claim 16, further comprising means for determining the power control parameter based on an existing particular link transmitter power of the one of the links. The transceiver node of claim 18, further comprising a metrology component for measuring the total transmitter power and the particular coupled transmitter power. The transceiver node of claim 16 further comprising means for determining the power control parameter based on the particular link information indicating a priority level associated with the link. The transceiver node of claim 16, wherein the power control parameter is related to one of the following groups: a maximum of one of the specific link transmitter powers, a probability of granting, and a step of power change size. The transceiver node of claim 16, comprising: Combining components for combining at least two power control parameters according to different input parameters into one aggregate power control parameter; and using the component of the aggregate power control parameter for adjusting the power of the specific link transmitter. The transceiver node of claim 16, wherein the determining component comprises an execution component that performs one of indicating a smooth transition behavior when the existing total transmitter power of the transceiver node (122) approaches a maximum total transmitter power value A predetermined power allocation function. The transceiver node of claim 16, wherein the decision component includes a decision component that determines the power control parameter based on a predetermined threshold of the total transmitter power. The transceiver node of claim 16, comprising a base station unit. A communication system (100) having a power control component and including a transceiver node (122) communicable with a plurality of mobile terminals (110), the communication system comprising: a receiving component at which the transceiver node a wireless link receiving a transmitter power change request from one of the mobile terminals; determining means for determining at least one power control parameter of the link based on an existing total transmitter power of the transceiver node; and a distribution component, The transmitter power is distributed to the link based on the determined power control parameter. The communication system of claim 26, wherein the existing total transmitter power substantially represents all downlink power resources, shares and specific links for the transceiver node (122) at a particular point in time. The communication system of claim 26, further comprising means for determining the power control parameter based on an existing particular link transmitter power of the one of the links. The communication system of claim 26, further comprising means for determining the power control parameter based on the particular link information indicating the priority level associated with the link. The communication system of claim 29, further comprising a transport component for transmitting the particular link information from a network-based control unit (124) of the communication system to the transceiver node (122). The communication system of claim 26, wherein the power control parameter is related to an item selected from the group consisting of: a maximum value of the specific link transmitter power, a probability of granting, and a step size of a power change . The communication system of claim 26 is selected from the group consisting of a code division multiplex access (CDMA) system, a wideband code division multiplex access (WCDMA) system, and a crossover multiplex processing (OFDM). The system, and a multi-carrier power amplifier (MCPA) system.